Background:

Plant mitochondrial genomes are unusual in
their diversity of structure and rapidity of change. A recent comparison of
the complete sequences of mitochondrial DNA from two eudicot species showed
that, although most of the known coding regions are very conserved, large
intergenic regions show no sequence similarity. The regions between genes
have important roles in the rapid structural evolution seen for plant
mitochondrial genomes. Moreover, these “non-coding” regions can become
functional as components of chimeric genes that have been described as being
responsible for several cases of cytoplasmic male sterility (CMS).

Why Sequence:

In order to
understand how non-coding regions of mitochondrial genomes contribute to
their structural and functional diversity, it is necessary to examine
closely related species. To address these issues, six mitochondrial genomes
within the genus Zea, including fertile and CMS mtDNAs of maize, are
being sequenced and compared to the the mtDNA sequences of more distant
relatives, Tripsacum dactyloides and Sorghum bicolor.